A belief system called Gnosticism was taking root in Christianity at the time the book of John was being written that taught there was a supreme and unknowable Being, which they designated as the "Monad." The Monad produced various gods, who in turn produced other gods, and one of these gods called the "Demiurge" created the earth and then ruled over it as an angry, evil and jealous god. Gnostics believe this evil god was the god of the Old Testament who is called"Elohim" and so the Monad had to send another god known as the "Christ"to bring special knowledge to mankind and free them from the influence of the evil Elohim. And this is why the gnostics do not seek salvation from repenting of their sin(but rather from the ignorance of which sin is a consequence) that they believe the evil creator God and his angels caused. They emphasize salvation of select humans from bodily existence through their awakening to the knowledge of their original divine identity. I believe the Apostle John had them on his mind when he wrote the Epistle of 1 John saying you must realize you have sin and repent. John was not talking to the already saved Christian as the Catholics would like you to believe.
You "believe," but what evidence do you have? If there is no evidence, then be very, very careful about basing your interpretation of Scripture on simply what you believe to be the case.
I see this 1 John chapter 1 and 2 as we are either walking in our old dead nature if we are into sin. Or we are walking in the spirit if we are not into sin.
Chapter 1
6 "If we say that we have fellowship with him, and walk in darkness, we lie, and do not the truth:"
6. Not in him because we are either not saved or have not put on the new man.
7"But if we walk in the light, as he is in the light, we have fellowship one with another, and the blood of Jesus Christ his Son cleanseth us from all sin."
7. In him because we are saved and have put on the new man.
8 "If we say that we have no sin, we deceive ourselves, and the truth is not in us."
8. Not in him because we are either not saved or have not put on the new man.
9 "If we confess our sins, he is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness."
9. In him because we are saved and have put on the new man.
10 "If we say that we have not sinned, we make him a liar, and his word is not in us."
10. Not in him because we are either not saved or have not put on the new man.
Perhaps you would like to address what I have posted on this passage, not to mention the rest of the context of 1 John and the NT.
The reason we shall not fulfill the lust of the flesh because there's no lust in him. It's the "in him" that I believe is not understood.
Galatians 5:16 This I say then, Walk in the Spirit, and ye shall not fulfil the lust of the flesh
Why would Paul even need to say that if believers don't sin? Much of the NT consists of commands for believers that are utterly meaningless if believers don't sin. Here is a small sampling:
Rom 12:3 For by the grace given to me I say to everyone among you not to think of himself more highly than he ought to think, but to think with sober judgment, each according to the measure of faith that God has assigned.
...
Rom 12:9 Let love be genuine. Abhor what is evil; hold fast to what is good.
Rom 12:10 Love one another with brotherly affection. Outdo one another in showing honor.
Rom 12:11 Do not be slothful in zeal, be fervent in spirit, serve the Lord.
Rom 12:12 Rejoice in hope, be patient in tribulation, be constant in prayer.
Rom 12:13 Contribute to the needs of the saints and seek to show hospitality.
Rom 12:14 Bless those who persecute you; bless and do not curse them.
Rom 12:15 Rejoice with those who rejoice, weep with those who weep.
Rom 12:16 Live in harmony with one another. Do not be haughty, but associate with the lowly. Never be wise in your own sight.
Rom 12:17 Repay no one evil for evil, but give thought to do what is honorable in the sight of all.
Rom 12:18 If possible, so far as it depends on you, live peaceably with all.
Rom 12:19 Beloved, never avenge yourselves, but leave it to the wrath of God, for it is written, “Vengeance is mine, I will repay, says the Lord.”
Rom 12:20 To the contrary, “if your enemy is hungry, feed him; if he is thirsty, give him something to drink; for by so doing you will heap burning coals on his head.”
Rom 12:21 Do not be overcome by evil, but overcome evil with good.
1Co 6:18 Flee from sexual immorality. Every other sin a person commits is outside the body, but the sexually immoral person sins against his own body.
1Co 6:19 Or do you not know that your body is a temple of the Holy Spirit within you, whom you have from God? You are not your own,
1Co 6:20 for you were bought with a price. So glorify God in your body.
Eph 5:15 Look carefully then how you walk, not as unwise but as wise,
Eph 5:16 making the best use of the time, because the days are evil.
1Th 4:3 For this is the will of God, your sanctification: that you abstain from sexual immorality;
1Th 4:4 that each one of you know how to control his own body in holiness and honor,
1Th 4:5 not in the passion of lust like the Gentiles who do not know God;
1Ti 6:9 But those who desire to be rich fall into temptation, into a snare, into many senseless and harmful desires that plunge people into ruin and destruction.
1Ti 6:10 For the love of money is a root of all kinds of evils. It is through this craving that some have wandered away from the faith and pierced themselves with many pangs.
1Ti 6:11 But as for you, O man of God, flee these things. Pursue righteousness, godliness, faith, love, steadfastness, gentleness.
2Ti 2:14 Remind them of these things, and charge them before God not to quarrel about words, which does no good, but only ruins the hearers.
2Ti 2:15 Do your best to present yourself to God as one approved, a worker who has no need to be ashamed, rightly handling the word of truth.
2Ti 2:16 But avoid irreverent babble, for it will lead people into more and more ungodliness,
...
2Ti 2:21 Therefore,
if anyone cleanses himself from what is dishonorable, he will be a vessel for honorable use, set apart as holy, useful to the master of the house, ready for every good work.
2Ti 2:22 So flee youthful passions and pursue righteousness, faith, love, and peace, along with those who call on the Lord from a pure heart.
2Ti 2:23 Have nothing to do with foolish, ignorant controversies; you know that they breed quarrels.
Heb 13:5 Keep your life free from love of money, and be content with what you have, for he has said, “I will never leave you nor forsake you.”
(All ESV.)